1. Field of the Invention
The present invention relates to a structure for fastening a flat Braun tube to a cabinet, and more particularly, to an improved structure for fastening a flat Braun tube to a cabinet, which can prevent damage to a panel and reduce assembly working-hours.
2. Background of the Related Art
The Braun tube(a cathode ray tube) is used in a TV receiver or a display, and particularly, the flat Braun tube becomes popular recently because the flat Braun tube is advantageous in that a distortion of image can be reduced in comparison to a curved surfaced Braun tube, resulting to provide an image close to an actual image.
Referring to FIG. 1, the flat Braun tube is provided with a rectangular frame of a rail 2 attached on an inside surface of a flat panel 1, and a mask 3 having a plurality of slits bonded to the rail 2 under tension. And, there are a funnel 4 of a bulb form with a neck portion 4a at rear thereof bonded to a periphery of the inside surface of the panel 1, an electron gun 5 sealed in the neck portion 4a for emitting electron beams for red, green, and blue colors, and deflection yokes 6 on outer circumference of the neck portion 4a adapted to form vertical/horizontal uniform magnetic fields for deflection of the electron beams. As shown in FIGS. 2 and 3, the foregoing flat Braun tube is encased in front/rear cabinets 7 and 8, and the flat Braun tube 9 and the front cabinet 7 are fastened together by a compression band 10. The compression band 10, formed of a metal which expands and contracts on heating/cooling, has a rectangular form in overall. There is a lug 11 at each corner of the compression band 10 for fastening to the front cabinet 7. In order to fasten the compression band 10 and the panel 1, at first adhesive tape 12 is attached on an outer circumference of the panel 1, the compression band 10 is heated to lengthen an inner circumference of the compression band 10 longer than at least the outer circumference of the panel 1. Then, the panel 1 with the adhesive tape 12 attached thereto is inserted inside of the compression band 10 and cooled down at a room temperature, to leave the compression band 10 shrink around the outer circumference of the panel 1, thereby fastening the compression band 10 and the panel 1. In the meantime, the panel 1 with the compression band 10 fastened thereto is fastened to the front cabinet 7 by bringing the lugs 11 at four corners of the compression band 10 into a close contact with an inside of the front cabinet 7, and fastening the compression band 10 and the front cabinet together by means of fastening means, such as screws. For reference, the adhesive tape 12 attached along the outer circumference of the panel 1 acts as an insulator which prevents transmission of a high temperature of about 400.degree. C. applied in lengthening the compression band 10 to the outer circumference of the panel 1 directly, strengthens the adhesive force between the panel 1 and the compression band 10 as the adhesive tape 12 is melt by the heat applied to the compression band 10, and prevents the outer circumference of the panel 1 from being damaged and broken by the compression band 10.
However, the structure for fastening a flat Braun tube to a cabinet by means of the related art compression band 10 has the following problems.
First, in a case the lengthening of the compression band 10 is inadequate, with the outer circumference of the panel 1 being equal to or greater than the inner circumference of the compression band 10, a forced insertion of the compression band 10 to inside of the panel 1 may cause breakage of a corner of the panel 1, which is relatively weak. And, the forced insertion of the compression band 10 to inside of the panel 1 may push the adhesive tape 12 away from the outer circumference. Opposite to this, an excessive lengthening of the compression band 10 over a limit of the lengthening causes a poor fastening with the panel 1 due to a limit in contraction.
Second, the panel 1, under an excessive contraction, is contracted together with the compression band 10 at cooling down the compression band 10, to deteriorates landing or explosion proof characteristics of the flat Braun tube. Particularly, as shown in FIG. 4, in a case of an 22" panel 1, it is found that the panel 1 is deformed inwardly by approx. 6 mils(=152 .mu.m) at evacuation of the flat Braun tube, which becomes serious with a deformation ratio of 10% when the compression band 10 is contracted.
Third, the fastening of the compression band 10 with the panel 1 which requires heating the compression band 10, to lengthen the compression band 10, cooling the compression band 10 for compression onto the panel 1 has a problem of requiring many working-hours.